1. Field of the Invention
This invention relates to a method of controlling the stroke frequency of a forging machine with a mechanical stroke drive for the stroke movement of a forging punch and a hydraulic drive connection between stroke drive and forging punch, and to a forging machine for carrying out this method.
2. Description of the Prior Art
Such forging machines are available in various designs, where a crank or eccentric drive is used as stroke drive, whose stroke movement is transferred to the forging punch via a hydraulic drive connection, for which purpose the stroke drive actuates for instance a piston pump, whose pump space is hydraulically connected with a working cylinder associated to the forging punch. These forging machines provide for an easy overload protection and an adjustment of the stroke position with a high forging efficiency by changing the hydraulic volume in the hydraulic drive connection. So far, however, the stroke numbers of the forging punches can merely be controlled via the mechanical drive, which due to the losses of kinetic energy occuring during a reduction of the rotational speed only provides for a rather restricted range of control.